Downregulation of NIN/RPN12 binding protein inhibit the growth of human hepatocellular carcinoma cells

RPNs Levels Are Prognostic and Diagnostic Markers for Hepatocellular Carcinoma

The ribophorin family (RPN) is an essential regulatory subunit of the proteasome. By influencing the ubiquitin-proteasome system activity, ribophorins (RPNs) are responsible for almost all physiology and pathology processes of mammalian cells. Nevertheless, little is known about the role of RPNs in HCC. In this work, we first evaluated the transcriptional levels and the prognostic and diagnostic value of RPNs based on the public database. Firstly, we found all RPNs were surprisingly consistently upregulated in HCC tissues. Moreover, the RPNs' expression pattern is correlated with HCC tumor grade. The TCGA HCC platforms' data indicated that RPN2, RPN3, RPN6, RPN9, RPN10, RPN11, and RPN12 have robust diagnosis values. Then, survival analysis revealed that the high expression of RPN1, RPN2, RPN4, RPN5, RPN6, RPN9, and RPN11 was correlated with unfavourable HCC overall survival. Then, genetic alteration, immune infiltration feature, gene-genes network, and functional enrichment for RPNs indicated that RPNs have many potential biosynthesis activities expert for UPS functions. Moreover, western blot and qRT-PCR results confirmed these results. The silencing of RPN6 and RPN9 significantly reduced HCC cells' proliferation, migration, and invasion ability in vitro. An in vivo tumor model further validated the oncogene effect of RPN6 on HCC cell growth. Moreover, RPN6 and RPN9 could promote cell migratory and invasive potential by affecting the epithelial-mesenchymal transition (EMT) process. In summary, this study suggests that the RPN family has the potential to be potential biomarkers and targets for HCC.

NOB1: A Potential Biomarker or Target in Cancer

Human NIN1/RPN12 binding protein 1 homolog (NOB1), an RNA binding protein, is expressed ubiquitously in normal tissues such as the lung, liver, and spleen. Its core physiological function is to regulate protease activities and participate in maintaining RNA metabolism and stability. NOB1 is overexpressed in a variety of cancers, including pancreatic cancer, non-small cell lung cancer, ovarian cancer, prostate carcinoma, osteosarcoma, papillary thyroid carcinoma, colorectal cancer, and glioma. Although existing data indicate that NOB1 overexpression is associated with cancer growth, invasion, and poor prognosis, the molecular mechanisms behind these effects and its exact roles remain unclear. Several studies have confirmed that NOB1 is clinically relevant in different cancers, and further research at the molecular level will help evaluate the role of NOB1 in tumors. NOB1 has become an attractive target in anticancer therapy because it is overexpressed in many cancers and mediates different stages of tumor development. Elucidating the role of NOB1 in different signaling pathways as a potential cancer treatment will provide new ideas for existing cancer treatment methods. This review summarizes the research progress made into NOB1 in cancer in the past decade; this information provides valuable clues and theoretical guidance for future anticancer therapy by targeting NOB1.

Silencing NOB1 Can Affect Cell Proliferation and Apoptosis Via the C-Jun N-Terminal Kinase Pathway in Colorectal Cancer

OBJECTIVES

To investigate the bio-functions and the molecular mechanisms of NIN1/proteasome 26S subunit non-ATPase 8 binding protein 1 homolog (NOB1) in colorectal cancer cells.

METHODS

NOB1 expression was silenced using si-RNA in SW480 and LoVo cells. The transfection efficiency was measured by western blotting and RT-qPCR. Subsequently, the proliferation of SW480 and LoVo cells was determined using both MTT assay and colony-formation assay. Apoptosis and cell cycle analysis were determined using flow cytometry.

RESULTS

Compared with the normal control (NC) and scramble cells, si-NOB1 could significantly attenuate the proliferation, colony-formation ability and cell percentage of S stage (p < 0.05). Additionally, at the phosphorylation level, si-NOB1 could notably increase the expression of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38.

CONCLUSIONS

Inhibition of NOB1 expression suppressed the proliferation, and promoted the apoptosis through regulation of the JNK signaling pathway.

miR‑145 inhibits human non‑small-cell lung cancer growth by dual-targeting RIOK2 and NOB1

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-associated mortality worldwide. Right open reading frame kinase 2 (RIOK2) and nin one binding protein (NOB1) are important accessory factors in ribosome assembly. In our previous study, RIOK2 and NOB1 were revealed to be highly expressed in NSCLC, and were associated with the clinicopathological characteristics of patients with NSCLC, i.e. TNM clinical stage, lymph node metastasis and differentiation. In addition, RIOK2 expression was correlated with NOB1. To further explore the mechanism and the RIOK2 and NOB1 signaling pathway, microRNA (miR) regulation was analyzed. The tumor suppressor miR‑145 has been reported to be lowly expressed in numerous types of human cancer; in the present study, the expression levels of miR‑145 were decreased in patients with NSCLC. Furthermore, RIOK2 and NOB1 were predicted to be the direct targets of miR‑145 using bioinformatics software; this was further validated using a dual luciferase reporter assay. In addition, the protein expression levels of RIOK2 and NOB1 were inhibited in response to miR‑145 overexpression, thus resulting in the suppression of cell viability, migration and invasion. These results suggested that RIOK2 and NOB1 may be potential targets in the treatment of NSCLC, and miR‑145 may be considered a therapeutic inhibitor of both genes.

Inhibition of NOB1 by microRNA-330-5p overexpression represses cell growth of non-small cell lung cancer

MicroRNAs (miRNAs) play critical roles in the development and progression of various cancers, including non-small-cell lung cancer (NSCLC). Studies have suggested that miR-330-5p is involved in the progression of several cancers. However, the role of miR-330-5p in NSCLC remains unclear. We investigated the effect on and mechanism of miR-330-5p in the progression of NSCLC. We found that miR-330-5p was significantly downregulated in NSCLC tissues and cell lines as detected by real-time quantitative polymerase chain reaction (RT-qPCR). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), bromodeoxyuridine (BrdU), colony formation and cell cycle assays showed that overexpression of miR-330-5p markedly inhibited cell growth. Annexin V-FITC/PI and caspase-3 activity assays showed that overexpression of miR-330-5p significantly promoted cell apoptosis of NSCLC cells. Bioinformatics analysis and dual-luciferase reporter assays confirmed NIN/RPN12 binding protein 1 (NOB1) as a target gene of miR-330-5p. RT-qPCR and Western blot analysis showed that overexpression of miR-330-5p inhibited the expression of NOB1 as well as cyclin D1 and cyclin-dependent kinase 4 in NSCLC cells. Moreover, overexpression of NOB1 markedly reversed the miR‑330-5p-mediated inhibitory effect on NSCLC cell growth. Correlation analysis showed that miR‑330-5p expression was inversely correlated with NOB1 mRNA expression in NSCLC tissues. Taken together, our results indicate that miR-330-5p inhibits NSCLC cell growth through downregulation of NOB1 expression. Our study suggests that miR-330-5p may serve as a potential therapeutic target for the treatment of NSCLC.

NOB1 silencing inhibits the growth and metastasis of laryngeal cancer cells through the regulation of JNK signaling pathway

Nin one binding protein (NOB1) plays important roles in the synthesis and degradation of proteins, thus having effects on the cellular process. In the present study, the expression level of NOB1 in laryngeal cancer patients was detected by quantitative PCR and western blotting, and the effect of NOB1 on growth and metastasis of laryngeal cancer cells was explored. Silence of NOB1 was found to inhibit the proliferation of laryngeal cancer cells, arrest cell cycle and induce cell apoptosis. NOB1 silence was also found to inhibit the migration and invasion of laryngeal cancer cells and to downregulate the protein levels of matrix metalloproteinases (MMPs)-2 and MMP-9. Further mechanism study revealed that the JNK signaling pathway was involved in the function of NOB1. Our present results suggest that NOB1 plays an oncogenic role in laryngeal cancer cells through the regulation of JNK signaling pathway, and lays a theoretical foundation for further exploration of NOB1.

MiR-192 suppresses the tumorigenicity of prostate cancer cells by targeting and inhibiting nin one binding protein

Nin one binding (NOB1) protein has been identified as an oncogene in various human cancers, including prostate cancer. MicroRNAs (miRs) have also been recognized as novel regulatory molecules of gene expression. The present study aimed to discover potential miRs that target NOB1 and regulate NOB1 expression in prostate cancer. miR-192, which is an important regulator of numerous cancers, was found to be significantly downregulated in prostate cancer cells. Moreover, we noted that miR-192 overexpression markedly inhibited the proliferation, colony‑forming ability, and migratory capacity of the prostate cancer cells. miR-192 overexpression also induced cell cycle arrest in the G1 phase, as shown by flow cytometry. Bioinformatics analysis results revealed that NOB1 was a possible candidate target gene of miR-192. This discovery was further verified through dual‑luciferase reporter assay, RT-qPCR, and western blot analysis. We suggest that miR-192 directly regulates the mRNA and protein expression of NOB1. Furthermore, miR-192 inhibited the expression of p38 mitogen-activated protein kinase. The results of our study indicated that miR-192 negatively regulated NOB1 expression and impaired the tumorigenicity of prostate cancer cells. Therefore, we suggest that targeting miR-192 and NOB1 is a novel strategy which will assist in the development of new therapeutics that will be used in the future to prevent and treat prostate cancer.

Downregulation of NOB1 inhibits proliferation and promotes apoptosis in human oral squamous cell carcinoma

NIN1/RPN12 binding protein 1 homolog (NOB1) facilitates the maturation of the 20S proteasome and is then degraded by 26S proteasome to complete 26S proteasome biogenesis. It also accompanies the pre-40S ribosomes during nuclear export and is cleaved at D-site of 20S pre-rRNA to form mature 18S rRNA in growing cells. NOB1 was reported to be involved in the development of several types of cancer. However, the role of NOB1 in oral squamous cell carcinoma (OSCC) has not been addressed. In the present study, the expression of NOB1 in 50 OSCC patients with different genders, ages, TNM and pathological grades was detected using immunohistochemistry and western blotting. A loss-of‑function study was carried out by the lentivirus‑mediated siRNA knockdown of NOB1 in the CAL27 and TCA-8113 OSCC cell lines. The results showed that, NOB1 expression increased with pathological grades. In the CAL27 and TCA-8113 cell lines, knockdown of NOB1 in OSCC cells decreased cell proliferation, colony formation, increased cell apoptosis and also induced cell cycle arrest in the S phase. The results suggested that NOB1 is important in OSCC development and serves as a candidate indicator of aggressiveness and a therapeutic target of OSCC.

MicroRNA-184 promotes proliferation ability of glioma cells by regulating FOXO3

OBJECTIVES

To investigate the effect of microRNA (miR-184) on regulating the genesis, development and proliferation of glioma cells.

METHODS

Lipidosome was used to transfect miR-184 mimic and inhibitor to glioma cell line, and the cell proliferation ability changes were determined by MTT and plate cloning experiment after the transfection. WB test was used to measure the levels of cyclinD1, p27 and FOXO3. Meanwhile, QPCR was used to detect miR-184 expression in glioma cell line, glioma tissues and adjacent tissues. Luciferase experiment was used to test 3'UTR gene targeting regulation of miR-184 and FOXO3.

RESULTS

QPCR results showed a significant lower miR-184 expression level in glioma cell line and glioma tissues than that in juxtacancerous tissue. MTT and plate cloning experiments have shown that after over-expressing of miR-184, the cell proliferation capacity of glioma U87 and T98G was significantly increased, which was significantly inhibited after the inhibition of miR-184. WB results showed a lower expression level of p27 in U87 and T98G cells, and a higher expression level of cyclinD1 after over-expressing of miR-184 was observed. However, a lower expression level of cyclinD1 and a higher expression level of p27 after the inhibition of miR-184. The luciferase activity was inhibited after the over-expressing of miR-184.

CONCLUSIONS

MiR-184 can affect the proliferation abilities of glioma cells and regulate the cell cycle related protein. It plays an important role in the occurrence and development of gliomas.

Silencing NOB1 enhances doxorubicin antitumor activity of the papillary thyroid carcinoma in vitro and in vivo

Doxorubicin (DOX), a broad‑spectrum anthra-cyclin, is in wide clinical use for the treatment and prevention of thyroid cancer. However, the effectiveness of the treatment remains limited due to inherent tumor resistance to DOX. Results of a previous study demonstrated that downregulation of NIN1/RPN12 binding protein 1 homolog (NOB1) expression via adenovirus expression vector carrying NOB1 siRNA (Ad/sh-NOB1) induced cancer apoptosis and increased the radiosensitivity of papillary thyroid carcinoma (PTC) cells. However, whether knockout NOB1 can decrease DOX resistance remains unclear. Therefore, in the present study, the effect of Ad/sh-NOB1 infection, independently or in combination with DOX, was determined in a PTC cell line to identify more effective therapeutics against PTC cancer. Furthermore, tumor growth ability in nude mice was determined to identify the combination treatment effect in tumorigenesis in vivo. The results showed that Ad/sh-NOB1 combined with DOX treatment in PTC cells significantly suppressed proliferation, colony formation, migration and invasion, and induced cell apoptosis and arrest in the G0/G1 stage as compared to Ad/sh-NOB1 or DOX monotherapy. We also found that this combination suppressed the tumor growth of a nude mouse model as compared to Ad/sh-NOB1 or DOX monotherapy. In addition, Ad/sh-NOB1 combined with DOX treatment significantly increased activation of the p38 MAPK pathway, which may contribute to inhibition of PTC cell growth and decreased DOX resistance. Taken together, the experimental results indicate that Ad/sh-NOB1 combined with DOX treatment is a potential drug candidate for the treatment of papillary thyroid carcinoma.

Positive nin one binding protein expression predicts poor outcome in prostate cancer

Nin one binding protein (NOB) 1 has been reported to be involved in cancer. However, the role of NOB1 in prostate cancer (PCa) has yet to be elucidated. The present study aimed to investigate the clinical role of NOB1 in PCa. The gene and protein expression levels of NOB1 were detected using quantitative polymerase chain reaction and western blot analysis in fresh samples of PCa and matched adjacent noncancerous tissues (n=32). NOB1 expression was also assessed using immunohistochemistry in a large number of patients with PCa (n=456) and paired adjacent noncancerous tissues between December 2003 and December 2010. The association between NOB1 expression and clinicopathological features and prognosis was investigated. The expression of NOB1 was found to be higher in the fresh samples of PCa than in the paired adjacent noncancerous tissues at the gene and protein levels. Immunohistochemistry revealed that the positive expression rates of NOB1 in PCa and the paired adjacent noncancerous tissues were 53% (242/456) and 6.1% (28/456), respectively. NOB1 expression was significantly correlated with Gleason score (P<0.001) and distant metastasis (P<0.001). Furthermore, patients with PCa with positive NOB1 expression had lower overall survival and recurrence‑free survival (RFS) compared with those with negative NOB1 expression. Multivariate analysis showed that NOB1 was an independent marker of RFS (hazard ratio, 3.45; 95% confidence interval, 1.41‑6.35; P=0.006). These findings suggest that NOB1 may be a potential prognostic indicator for PCa.

Adenovirus-mediated siRNA targeting NOB1 inhibits tumor growth and enhances radiosensitivity of human papillary thyroid carcinoma in vitro and in vivo

NIN1/RPN12 binding protein 1 homolog (NOB1), a ribosome assembly factor, plays critical roles in tumor progression and development. Previously, we reported that overexpression of NOB1 is correlated with the prognosis of patients with papillary thyroid carcinoma (PTC). Little is known, however, concerning its role in PTC. The aims of the present study were to investigate the association of NOB1 expression with tumor growth and radiosensitivity of human PTC. A recombinant adenovirus expression vector carrying NOB1 was constructed and then infected into the human PTC cell line TPC-1. Cell proliferation, cell cycle distribution, apoptosis, migration and invasion in vitro and tumor growth in vivo were determined after downregulation of NOB1 by RNAi. Additionally, the in vitro and in vivo radiosensitivity of PTC cells was determined by clonogenic cell survival assay and a mouse xenograft model, respectively. The results showed that downregulation of NOB1 expression using RNAi in TPC-1 cells significantly inhibited cell proliferation, migration and invasion and induced cell apoptosis in vitro, and suppressed tumor growth in vivo, as well as enhanced the in vitro and in vivo radiosensitivity of PTC cells. Moreover, our results also showed that downregulation of NOB1 was able to significantly activate constitutive phosphorylation of p38 MAPK, which might contribute to the inhibition of PTC cell growth. These findings suggest that NOB1 may be a potential therapeutic target for the treatment of PTC.

Knockdown of NOB1 expression inhibits the malignant transformation of human prostate cancer cells

Nin one binding-1 protein (NOB1) is a kind of zinc protein involved in ribosome biogenesis and controlled proteolysis. To explore the function of NOB1 in human prostate malignancy, we analyzed the expression of NOB1 in prostate cancer and found that NOB1 was elevated in prostate cancer tissues compared to the adjacent normal tissues. Knockdown of NOB1 by lentivirus-shRNA inhibited the proliferation and colony-formation ability of PC-3 and DU145 prostate cancer cells. Cell cycle analysis showed that silencing of NOB1 caused G0/G1 phase arrest and a slight decrease in S phase (P < 0.05). Furthermore, knockdown of NOB1 significantly suppressed the mobility of PC-3 and DU145 prostate cancer cells (P < 0.05). Collectively, these findings suggested that NOB1 might be involved in tumorigenecity of prostate cancer, and could be a potential molecular target for prostate cancer gene therapy.

Lentivirus-mediated knockdown of NOB1 suppresses the proliferation of colon cancer cells

NOB1 is important for ribosome biogenesis and protein degradation. Previous studies showed that it could regulate the growth and colony-formation ability of ovarian, breast and hepatocellular carcinoma cells. However, its function in colon cancer cells is largely unknown. In this study, we found that NOB1 could express in 6 different colon cancer cell lines. Lentivirus-mediated shRNA targeted NOB1 could suppress the endogenous gene expression. NOB1 depletion significantly inhibited cell proliferation and colony formation ability, as determined by MTT and colony formation assays. Flow cytometry analysis showed NOB1 silencing arrested cell cycle in G0 / G1 phase. Moreover, the percentage of cells at sub-G1 phase dramatically increased after NOB1 knockdown. These results indicate that NOB1 may play an important role in the growth and tumorigensis of colon cancer and knockdown of NOB1 may be a potential therapeutic method for colon cancer in the future.

Gene silencing of NOB1 by lentivirus suppresses growth and migration of human osteosarcoma cells

NIN1/RPN12 binding protein 1 homolog (Saccharomyces cerevisiae) (NOB1) encodes a chaperone protein that joins the 20S proteasome with the 19S regulatory particle in the nucleus and facilitates the biogenesis of the 26S proteasome, which plays a role in maintaining cellular homeostasis by controlling protein degradation. In order to investigate the role of NOB1 in osteosarcoma, NOB1 protein expression in human osteosarcoma cell lines was assessed using western blot analysis. Lentivirus-mediated short hairpin RNA was employed to knock down NOB1, and the effects of NOB1 silencing on cell growth were assessed using MTT, colony formation and cell cycle assays. Cell migration was observed using the Transwell assay. In addition, the expression levels of E-cadherin and β-catenin were examined by western blot analysis. Functional analysis indicated that NOB1-knockdown markedly inhibited cell growth and caused G2/M-phase arrest in human osteosarcoma cells. Furthermore, NOB1 inhibition decreased cell migration and increased E-cadherin and β-catenin expression in U2OS cells. In conclusion, the present study suggested that NOB1 depletion may inhibit osteosarcoma development by increasing E-cadherin and β-catenin expression and, for the first time, indicated the potential of NOB1 as a target in osteosarcoma treatment.

Downregulation of NOB1 suppresses the proliferation and tumor growth of non-small cell lung cancer in vitro and in vivo

Non-small cell lung cancer (NSCLC) is a lethal disease due to the absence of effective diagnostic biomarkers and therapeutic targets. Therefore, novel molecular targets are critically needed to formulate new approaches for this devastating disease. In the present study, using quantitive real-time PCR and immunohistochemistry. we initially found that expression of the ribosome assembly factor NIN/RPN12 binding protein (NOB1) was elevated in the majority of NSCLC tissues when compared to that in the normal lung tissue counterparts, and its expression level was correlated with key pathological characteristics including tumor differentiation, stage and metastasis. Then, the recombinant lentiviral shRNA expression vector carrying NOB1 was constructed and infected into the human NSCLC A549 cell line. Cell proliferation, cell apoptosis, cell cycle distribution and colony formation ability in A549 cells were assessed following downregulation of NOB1 by siRNA. In addition, tumor growth ability in nude mice was evaluated to define the function of NOB1 in cell transformation and tumorigenesis. It was found that downregulation of NOB1 expression using the RNA silencing approach in A549 tumor cells significantly suppressed the proliferation and colony formation ability, and induced tumor apoptosis in vitro. Tumor growth was also suppressed in vivo. These data suggest that NOB1 is an important regulator of the tumorigenic properties of human NSCLC and may be used as a new promising diagnostic biomarker and a potential anticancer therapeutic target for NSCLC.

Expression of the NOB1 gene and its clinical significance in papillary thyroid carcinoma

OBJECTIVE

The aim of this study was to explore the relationships between expression of the NIN1/RPN12 binding protein 1 homologue gene (NOB1) in papillary thyroid carcinoma tissue and clinicopathological variables.

METHODS

Expression of NOB1 in papillary thyroid carcinoma, normal thyroid and benign thyroid tumour tissue was evaluated at the mRNA and protein levels by real-time fluorescence quantitative reverse transcription-polymerase chain reaction and immunohistochemistry, respectively. Relationships between immunohistochemical scores and several clinicopathological variables were also examined.

RESULTS

Expression of NOB1 mRNA and protein in papillary thyroid carcinomatissue was significantly higher than in normal thyroid tissue and benign thyroid tissue, while there was no significant difference between normal thyroid tissue and benign thyroid tumour tissue. A high level of NOB1 protein expression was associated with large tumour size and Union for International Cancer Control stage, but was not significantly correlated with sex or age.

CONCLUSIONS

Compared with normal thyroid and benign thyroid tumour tissue, papillary thyroid carcinomas showed higher expression of NOB1, which indicates that the expression level of the NOB1 gene in the thyroid may play a key role in the occurrence and development of papillary thyroid carcinoma.